Characterization And Gene Cloning Of Rice Dwarf And Narrow-leaf Mutant Dnl3

Rice is the most important food crop in the world. High yield is the most effective safeguard for food safety and sustainable agricultural development. An ideal plant type is basically essential for higher yielding rice production. As one kind of leaf shape, narrow leaf plays an important role in building the ideal plant type of rice. On the other hand, plant height is an agronomically important trait for grain yield since the higher plant is easy to be lodging and decreasing yield, whereas dwarf plant has a great harvest index because of improved lodging resistance and increasing use of hitrogen fertilizers. Here, we have conducted the map-based cloning and functional analysis of rice EMS-derived dwarf narrow-leaf mutant dnl3. The results of this study are summarized below:1. The dnl3 exhibited pleiotropic developmental defects. The mutant showed dwarf stem, reduced leaf width and slender grain shape. Microscopic analysis indicated that the narrow leaf phenotype arose from a marked reduction in the number of vascular bundles, while the dwarf stature was caused by the formation of foreshortened internodes and a reduced number of parenchyma cells. This latter abnormal was associated with a compromised cell division in the mutant, which is consistent with the transcriptional behavior of various cell division-related genes.2. Physiological assay indicated that the mutant was less responsive to exogenously supplied gibberellic acid than the wild type. Further, the transcription profiling of the genes involved in the synthesis and response of gibberellin suggested that the lesion in the mutant affected gibberellin signal transduction.3. The dnl3 phenotype was inherited as a single recessive gene, mapping within a 19.1 Kbp region of chromosome 12, which was found to harbor three open reading frames. Sequencing of the open reading frames revealed that the mutant carried an allele at one of the three genes which differed from the wild type sequence by 2 bp deletions; this gene encodes a cellulose synthase-like D4 (CSLD4) protein. Therefore, OsCSLD4 could be the candidate gene of DNL3. The DNL3 homologs are detected through plant kingdom, but with highly conserved protein sequence in monocotyledonous species such as maize and sorghum.4. Real-time PCR analysis showed that the DNL3 is expressed in all tested rice organs at the heading stage with much more transcripts abundance in flag leaves, roots and culms, and its protein was localized in the golgi.These results suggested that DNL3 plays important roles in leaf morphogenesis and vegetative growth of rice.